Currently Being ModeratedJul 3, 2013 8:14 AM (in response to BenyaminShuid)
The only way to find a lost iOS device is to use the Find my iPhone app or www.icloud.com. For this to work, you have to enable this feature on the lost device prior to loss. If you didn't do this, there is no way to find it. Neither Apple nor your carrier will find it for you.
Setup Find my iPhone:
Here's a good tip from Kappy on what to do if you device is lost or stolen: